Apparatus for dispensing adhesive



July 25, 1967 R. s. ESTABROOKS 3,332,581

APPARATUS FOR DISPENSING ADHESIVE 5 Sheets-Sheet 1 Filed March 15, 1965INVENTOR Roger S. Esfabrooks W Wwdw ATTORNEY y 9 R. s. ESTABROOKS3,332,581

APPARATUS FOR DISPENSING ADHESIVE Filed March 15, 19 65 5 Sheets-SheetJuly 25, 1967 R. s. ESTABROOKS I 3,332,581

APPARATUS FOR DISPENSING ADHESIVE Filed March 15, 1965 5 Sheets-Sheet 5o 0 24 3 J4 22 30 J6 Z8 48 Q- FIG-5 Filed March 15, 1965 July 25, 1967'R. s. ESTABROCKS 3,332,581

APPARATUS FOR DISPENSING ADHESIVE 5 Sheets-Sheet 4 July 25, 1967 FiledMarch 15, 1965 R. S. ESTABROOKS APPARATUS FOR DISPENSING ADHESIVE 5Sheets-Sheet 5 United States Patent 3,332,581 APPARATUS FOR DISPENSENGADHESIVE Roger S. Estabrooks, North Quincy, Mass, assignor toInternational Shoe Machine Corporation, Boston, Mass, a corporation ofMassachusetts Filed Mar. 15, 1965, Ser. No. 439,661 21 Claims. (Cl.222-481) This invention relates to apparatus for periodically dispensingfluid to a workpiece as the need for such fluid arises. It isparticularly adapted for use with a fluid which is handled at highpressures and temperatures, such as a thermoplastic adhesive.

Among the objects of this invention are:

To provide an improved method and apparatus for efficiently meltingsolid thermoplastic adhesive and thus render it fluid so as to beadaptable for use in a fluid dispensing system;

To provide an improved apparatus for dispensing fluid material at aconstant rate;

To provide an improved apparatus for periodically dispensing a fluid inprecise and equal amounts;

To provide an apparatus for dispensing fluid material in response to asignal, the time lag between the signal and the dispensing of thefluidibeing minimal;

To provide an improved valve apparatus having features of continuallyaccurate seating;

To provide a fluid dispensing apparatus which is compact and portable;

and to provide an improved knob for mechanically controlling theposition of a member.

Other object and advantages of the present invention will becomeapparent from the following description.

In the operation of this apparatus, the solid thermo plastic adhesive isloaded into a melting tank where a heating element at the base of thetank causes the adhesive to liquify. Once in a liquid state, theadhesive gravitates through an orifice in the base of the melting tankto a chamber located below the melting tank. The chamber houses a floatvalve the function of which is to obstruct the orifice in the base ofthe melting tank when the fluid in the chamber reaches a predeterminedlevel,

thereby terminating flow from the melting tank to the chamber. A-buttingthe float chamber is a second chamber; hereinafter referred to asthesump, with a passageway between them so as to allow the adhesive to flowfrom the float chamber to the sump. Housed within the sump is acontinuously operating gear pump, the inlet of which is immersed in theadhesive, thereby drawing in the adhesive forcing it through the pumpoutlet and into a pressure regulating device. The pressure regulatorconsists of a primary conduit, leading from the pump outlet to adispensing gun where the adhesive is dispensed, and two subsidiaryconduits, each one being in communication with the primary condut so asto divert and receive a portion of the flow of adhesive in the primaryconduit. Each of the subsidiary conduits directs the adhesive flowingtherein back to the sump. An obstruction is situated within one of thesubsidiary conduits and means are provided for varying the degree ofobstruction.

The amount of static pressure present in the primary and subsidiaryconduits can thus be varied by increasing or decreasing the degree ofobstruction in said subsidiary conduit. The other subsidiary conduitcontains a pressure relief valve. which is normally closed therebypreventing flow back to the sump, and is designed to open when apredetermined maximum static pressure in the conduits is attained. Meansare provided for varying the amount of static pressure necessary to openthe pressure relief valve. The portion of adhesive flowing in theprimary conduit and not diverted back to the sump then passes througha'filter before entering a distribution manifold.

3,332,581 Patented July 25, 1967 "ice The dispensing gun is connected tothe distribution manitold 'by means of a flexible hose so that theadhesive may be dispensed at any point within reach of the hose.

Incorporated in the dispensing gun is a valve, the function of which isto block or unblock the orifice in the tip of the nozzle, therebycontrolling the flow of adhesive to the workpiece. The valve is soconstructed as to form a perfect seal with the valve seat, therebyminimizing drip, leakage and wear. Means are provided for actuating thevalve and a device for sensing the need for adhesive controls the valveactuating means. Heating elements are situated at various locationsthroughout the apparatus for the purpose of maintaining the adhesive ata temperature level sufficient to prevent its solidification. Heatsensing elements are similarlydisposed throughout the apparatus for thepurpose of controlling the operation of the heating elements and therebypreventing overheating of the adhesive.

The invention will now be described in greater detail with reference tothe accompanying drawings wherein:

FIG. 1 is a side elevation of the apparatus;

FIG. 2 is a plan view of the apparatus taken on the line 22 of FIG. 1with the melting tank lid omitted;

FIG. 3 is a partially sectional view taken on the line- 3-3 of FIG. 2;

FIG. 4 is a plan view of the underside of the sump cover as viewed fromthe bottom of the sump;

FIG. 5 is a partially sectional view taken on the line 55 of FIG. 2;

FIG. 6 is a fragmentary elevation as seen from the left side of FIG. 1;

FIG. 7 is a partially sectional view taken along the line 77 of FIG. 2;

FIG. 8 is a partially sectional view taken along the line 8-8 of FIG. 7;

FIG. 9 is a partially sectional view of the dispensing and hose, shownin relatively large scale;

FIG. 10 is a side elevation of the dispensing gun as indicated by theline 10-10 of FIG. 9;

FIG. 11 is a sectional view of the nozzle and valve assembly taken alongthe line 11-11 of FIG. 9;

FIG. 12 is a fragmentary sectional view of the nozzle and valve assemblytaken along the line 12-42 of FIG. 11; and

FIG. 13 is a diagram of the electrical circuitry in the motor safetycontrol circuit.

Referring to the drawings (FIG. 1), the entire apparatus is mounted on aplatform 10, thereby facilitating portability. A melting tank 12, formedof aluminum or other heat conductive material, has a base 14 upon whichthe solid thermoplastic adhesive 16 rests as indicated in FIG. 5. Thetank 12 may be provided with a cover 13. Centrally located in the base14 is an orifice 18 which leads into another concentric orifice 20 of asmaller diameter, the bottom of the smaller orifice forming a valve seatwhich accommodates a ball-check valve 22. The ball is restricted tosubstantially vertical motion by four pins 24 which are mounted on theunderside of the base and lie on the circumference of a circle which isconcentric with the orifice in the base. The vertical motion of the ballis accomplished by means of a float arm 26 upon which the ball freelyrests, said float arm being pivotally mounted with a float 30 beingattached to one extremity of the float arm and a counterweight 32 beingslidably connected to the other extremity. The bottom of the ball 22rests on the float arm at a point in between the float arm pivot 28 andthe float 30. A float chamber 33, located underneath the melting tankbase 14-, houses the float valve mechanism 35 and receives the moltenadhesive as it flows through the orifices 18, 20 and past the ball-checkvalve 22. As the level of adhesive raises within the float chamber, thefloat 30 will similarly rise, cause ing the float arm 26 to swing aboutthe float arm pivot 28, thereby imparting an upward movement to theballcheck valve 22. This motion will terminate when the level ofadhesive is such that ball-check valve 22 is in contact with valve seatat the bottom of the smaller orifice 20 and the adhesive is unable toflow into the float chamber 33. As the level of the adhesive in thefloat chamber decreases a downward movement of the float arm 26 andball-check valve 22 will occur, thereby allowing adhesive to gravitatefrom the melting tank 12 into the float chamber. The level of adhesiveat which the ball-check valve 22 will obstruct the orifice 20 may bevaried by means of the slidably mounted counterweight 32 located at theextremity of the float arm 26. Shifting of the counterweight towards thefloat arm pivot 28 will decrease the buoyancy of the flot 30 therebycausing it to be more submerged in the adhesive, the effect being thatthe adhesive will have to rise to a higher level in order for theballcheck valve 22 to fully obstruct the orifice 20. The same result maybe obtained by maintaining the counterweight in a fixed position whilevarying its size. A decrease in the size of the counterweight would havethe same efiect as sliding a counterweight of fixed size inwardlytowards the float arm pivot 28. The present apparatus utilizes both ofthese methods in that the slidably mounted counterweight 32 has fixed toit a clip 34 for the purpose of retaining an additional weight 36. Anoverflow spout 38 is provided in one of the walls of the float chamberso as to limit the maximum allowable level of adhesive in the floatchamber.

Heat is supplied to the melting tank by means of an annular electricheating element 40 embedded in the melting tank base 14. i

The upper surface 42 of the melting tank base upon which the solidadhesive rests is flat with the exception of a plurality of radialtroughs 44 which are inclined downwardly from the periphery of themelting tank base to the center of the melting tank base where thetroughs terminate in the larger orifice 18. There is also an annulartrough 46 at the periphery of the melting tank base which is incommunication with the radial troughs 414.

, These troughs serve .a dual purpose in that they facilitate thegravitation of the molten adhesive to and through the orifices 18, 20and that they cause a more rapid rate of melting of the solid adhesivedue to the increased surface area of the melting tank base.

Abutting the float chamber 33 is a sump 48 with a passageway 50 betweenthem so as to allow the molten adhesive to flow unaided from the floatchamber into the sump, Thus, the level of adhesive in the sump cannot begreater than the level of adhesive in the float chamber.

A continuously operating gear pump 52 (PEG. 7) is located within thepump with its inlet port 54 being near the bottom of the sump so as toinsure its being immersed in the molten adhesive at all times. The pumis rigidly suspended from a hollow, cylindrical pump mount 56 which inturn is rigidly suspended from the sump cover 58. The pump shaft 60extends vertically upward into the hollow pump mount where a joint 62 ismade between the pump shaft 60 and an extension shaft 64. A pulley 66 isfixed to the extension shaft and an electric motor 68 (FIG. 1) or otherrotary driving means is connected to the pulley by a chain or belt 70.

i The molten adhesive is pumped to the pump outlet conduit 72 whichdirects the flow into the pressure regulating device 73. Said device(FIG. 3) consists of a pressure regulating block 74 in which isfabricated a primary conduit 76 and two subsidiary conduits 78, 80 eachof the subsidiary conduits being in communication with the primaryconduit so as to divert and receive a portion of the flow of moltenadhesive from the primary conduit. Both of the subsidiary conduitsreturn the adhesive to the sump 48 whereas the primary conduit directsthe adhesive towards the dispensing gun 82.

The first subsidiary conduit 78 consists of a pair of passages, locatedaskew, and interconnected by tapered orifice (FIG. 7) which acts as aseat for a needle valve 84, the purpose of said needle valve being toobstruct the flow of adhesive in the first subsidiary conduit 78 therebycontrolling the pressure and the flow rate in said subsidiary conduit.This, in turn, affects the pressure and flow rate of the adhesive in theprimary conduit 76. A decrease in the degree of obstruction which theneedle valve presents to the orifice 90 in the first subsidiary conduitcauses a greater rate of flow of adhesive through said subsidiaryconduit which in turn causes both the pressure and the flow rate in theprimary conduit 76 to decrease. The converse is true, in that anincrease in the degree of obstruction of the orifice 90 results in anincrease in the pressure and flow rate of the adhesive in the primaryconduit '76. Variation of the degree of obstruction which the needlevalve 84 presents to the orifice 90 is accomplished by means of arotatable pressure control rod 86, the tip of which forms the needlevalve, 84 itself. The pressure control rod extends from the exterior ofthe sump 48, through the sump cover 58 and into the interior of the sumpwhere a threaded portion 88 of the pressure control rod engages a tappedholein the pressure regulating block 74. The location of the tapped holeis such'that the longitudinal axis of the pressure control rod 86 andthe central axis of the orifice 90 coincide, thereby insuring that thetip of the pressure control rod which forms the needle valve 84 and theportion of the orifice 90 which forms the valve seat, will be inalignment.

In operation, as the pressure control rod 86 is rotated, an axial motionis simultaneously imparted to the control rod by reason of its threadedengagement with the pressure regulating block 74, thereby increasing ordecreasing the degree of obstruction which the needle valve 84 presentsto the orifice 90, depending on the direction of rotation of thepressure control rod.

Rotation of the pressure control rod 86 is facilitated by a regulatingknob 92 (FIGS. 7, 8) having a head portion and a shank portion, the headportion being of a greater diameter than the shank portion. Theperiphery of the head portion may be knurled to aid in the manualgripping of the knob. The regulating knob 92 is mounted in a supportbushing 94 so that the shank portion is free to rotate within saidsupport bushing. The support bushing 94 is rigidly mounted to a controlpanel 96. A centrally located internal bore 98 extends through theentire length of the regulating knob. The portion of said internal borewhich is located in the shank portion of the regulating knobaccommodates in a loose fit, the outer extremity of the pressure controlrod 86, thereby allowing axial movement of said rod within said bore.Rotary motion is transmitted from the regulating knob 92 to the pressurecontrol rod 86 by means of a pin 100 secured to the outer extremity ofthe pressure control rod and extending diametrally into a longitudinalslot 102 cut along the diameter of the shank portion of the regulatingknob.

Once the setting of the pressure control rod 86 has been fixed itbecomes desirable to maintain this setting and with this end in view alocking mechanism is made an integral part of the regulating knob 92.The portion of the internal bore 98 which is located in the head portionof the regulating knob accommodates, in a loose fit, a locking shaft104, the outer extremity of which is rigidly attached to a lock shaftknob 106, with the inner extremity extending into the shank portion ofthe regulating knob and threads being formed at said inner extremity. Arectangular locking bar 108 is slidably mounted in an oval shaped slot110 located in the shank portion of the regulating knob, thelongitudinal axis of said locking bar being perpendicular to thelongitudinal axis of said regulating knob, with the ends of said lockingbar protruding beyond the periphery of the shank portion of theregulating knob 92. A tapped hole is centrally positioned in the lockingbar and thereby engages the threaded portion of the locking shaft 104 sothat as the locking shaft is rotated on axial motion is imparted to thelocking bar, thereby drawing the protruding ends of the locking baragainst the rigidly fastened support bushing 94 and preventing rotarymotion of the regulating knob.

Obstructing the second subsidiary conduit 80 (FIG. 3) is a spring-biasedplunger 112 slidably contained in an internal bore 111. A helicalcompression spring 114 contained in said internal bore maintains theplunger in a position which fully obstructs the second subsidiaryconduit. A reactor surface 116 of the plunger is in communication withthe adhesive so that the plunger will retract from its obstructingposition when the force on the reactor surface exceeds force exerted bythe spring 114. The force needed to compress the spring may be varied bymeans of a plug 118 which is threaded to engage complementary threads inthe internal bore 111. Thus, the mechanism acts as a relief valve, thepurpose of which is to limit the maximum pressure within the system,thereby preventing leakage or rupture at locations throughout theapparatus subject to relatively large stresses.

The pressure regulating block 74 is rigidly mounted to the underside ofa distribution manifold 120, said manifold being an integral part of thesump cover 58. A continuation of the primary conduit 76 is located inthe underside of the distribution manifold. Directly above and incommunication with the primary conduit is a relatively large diameterbore 122, hereinafter referred to as the filter chamber, which extendsvertically upward from the termination of the primary conduit throughthe outer surface of the sump cover 58. A cup-shaped filter cap 124 ismounted in an inverted position on the sump cover above and concentricwith the filter chamber, thereby enclosing said chamber. Situated withinthe filter chamber 122 and concentric with it and the primary conduit isa hollow, cylindrical filter 126, the upper end of which abuts theceiling of the interior of the filter cap 124 and the lower end of whichabuts the bottom of the filter chamber so that the adhesive will flowfrom the primary conduit 76 to the interior of the filter 126. Thefilter cap 124 is mounted on the sump cover by threaded engagementtherewith, thereby allowing compression of the filter 126 between saidfilter cap and the bottom of the filter chamber so as to insure a tightseal at its ends. The filter is easily accessible for cleaning orreplacement purposes.

The portion of adhesive that is not returned to the sump via thesubsidiary conduits 78, 80 and hence remains in the primary conduit 76flows into the interior of the filter 126, passes through the filter tothe filter chamber 122 wherefrom it enters a distribution conduit 128.The distribution conduit is essentially an internal bore runninglongitudinally within the distribution manifold 120 and intersecting thefilter chamber 122 so as to receive the flow of adhesive from saidfilter chamber. A plurality of passages 130 extend vertically from thedistribution conduit 128 through the upper surface of the sump cover atwhich point fittings 132 connect each of said passages to a flexibleheated hose 134 which directs the adhesive to the applicator nozzle 82.Hoses may be connected to as many fittings as are available, theremaining unconnected fittings being closed by plugs 135.

Referring to FIG. 9 the flexible heated hose 134 is composed of threeconcentric layers of tubing, with a helical electric heating element 136located within and extending throughout the length of the hose so thatthe adhesive in the hose is in direct contact with the heating element.The innermost tube 138 conducts the adhesive and is in direct contactwith it. It is important that this tube be of a composition having highelectrical insulative qualities, high resistance to corrosion,flexibility and strength so that it may withstand the high pressures ofthe adhesive which it conducts. It is also desirable that the tube 138be heat insulative as the adhesive flowing within it is generally at avery high temperature. It has been found that the material commonlyknown as Teflon is suitable for these purposes. The intermediate tube140 is a stainless steel braid, the main function of which is to addstrength to and protect the tube 138. A number of such braided Teflonhoses complete with fittings 142 are available commercially. AlthoughTeflon has some heat insulative qualities the mmperature of the adhesiveis generally so high that the hose becomes extremely hot and for thisreason an outer tube 144 of fiberglass insulation is provided. Suchfiberglass tubes are also available commercially. To prevent the ends ofthe fiberglass tube 144 from becoming frayed they are covered by shrinktubing 146. As shown in FIG. 9 the shrink tubing covers both the end ofthe fiberglass tube 144 and the fitting 142.

The ends of the hose 134 are connected to hollow anchor blocks 148, bymeans of fittings 152, 154. The coiled electric heater 136 extendsbeyond the end of the hose and its fittings and is secured at its endsto electrically conductive anchor studs 156 which in turn are indirectlyfastened to the anchor blocks. Each anchor stud is surrounded by anelectrically insulative (Teflon) bushing 158 which in turn is containedwithin a sealing bushing 160. The sealing bushing 160 is fasteneddirectly to the anchor block 150- and serves the dual function ofholding the anchor stud in place as well as preventing leakage ofadhesive. The heater element 136, anchor stud 156, insulating bushing158, and sealing bushing 160 are so arranged as to have a common centralaxis. By extending the heating coil beyond the end of the hose and itsconnective fittings, and fixing it to anchor block 150, the difiicultiesencountered by anchoring the heating element to the hose or its fittingsitself are avoided in that a better seal is obtained and the heatingelement is more readily accessible for removal or replacement if suchneed should arise. A relatively short electrically insulative (Teflon)sleeve 162 is located within the innermost tube 138 so as to enclose theheating element 136 and thereby insulate it from making electricalcontact with the fittings 152, 154.

In addition to its function of securing the heating element 136, theanchor block 150 is an integral part of the dispensing gun 82. A nozzle164 having a passage therein is threaded to the underside of the anchorblock 150 so that the passage in the nozzle is in communication with thehollow of the anchor block, which in turn is in communication with thepassageway of the heated hose 134, thereby allowing molten adhesive toflow under pressure from the heated hose, through the anchor block 150and into the nozzle 164 where it is dispensed to a workpiece 166.Slidably mounted for vertical motion within the nozzle passage is aself-centering valve member 168 (FIGS. 11, 12) which cooperates with avalve seat 170 formed at the interior of the outlet end of the nozzle164 so that discharge of the adhesive is allowed or prevented, dependingon the position of the valve member 168. The construction andfunctioning of the self-centering valve member will be later describedin greater detail.

Vertical motion of the valve member is accomplished by means of a valvestem 172 to Which the valve member is connected by a pin 174, said valvestem being centrally located within the nozzle passage. The uppermostend of the valve stem is rigidly secured to a piston 176 slidablymounted within an air cylinder 17 8 so that the vertical motion of thepiston will be transmitted to valve member 168. An aperture is providedin the air cylinder base 180 so that the valve stem may pass andreciprocate therethrough. An air cylinder cap 182 is located at the topof the air cylinder and may be removed for access to the interior of theair cylinder. The anchor block 150 and air cylinder 178 are aligned bymeans of a hollow cylindrical spacer 184 interposed between them. Thespacer also acts as a means of insulating the air cylinder 1'78 from theheat radiated by the anchor block. It is preferable to fabricate thespacer from a material having relatively low heat conductivity such asstainless steel. The outside diameter of the spacer is made small enoughso that bolts 186 (FIG. may be passed through the air cylinder cap 182,air cylinder 178 and threaded into the anchor block 150 withoutinterfering with said spacer, thereby fastening and rigidifying thevarious components of the dispensing gun with respect to each other.

Compressed air is communicated to air cylinder chambers 188, 190 from asuitable source by means of passages 192 formed in the wall of the aircylinder 178. A device not shown (-microswitch, photoelectric cell,etc.) for sensingthe need for application of adhesive to a workpiece 166controls the actuation of a valve (not shown) disposed between thesource of air pressure and the air cylinder 178, which admits the airinto either of the air cylinder chambers 188, 190, thereby actuating thepiston 176, the vertical motion of which is transmitted to the valvemember 168 by means of the valve stem 172. When the compressed air is inair cylinder chamber 190 the valve member 168 will be unseated andadhesive will be continuously dispensed until the compressed air isdirected to air cylinder chamber 188 whereupon the valve memher 168 willbe seated and the flow of adhesive will stop.

Some of the uses in which this apparatus may be employed may requirethat the seating of the valve member 168 be instantaneous. To decreasethe time required to bring the valve member from a dispensing to anon-dispensing position, means for shortening the stroke of the valvestem are provided. A threaded portion 194 of the valve stem 172 that iscontained within the hollow spacer 184 engages a tapped hole, centrallylocated in the base of a cup-shaped limiting stop 196, similarlycontained within the hollow spacer, so that the upper end of thelimiting stop is directly below the lower surface of the air cylinderbase 180, with a clearance separating them. The amount of this clearancedetermines the stroke of the valve stem 172 which may be varied byrotating the valve stem with respect to the limiting stop 196. This isfacilitated by means of a screwdriver slot'198 cut in the upper surfaceof the piston 176 whereby the piston and valve stem may be rotated whilethe limiting stop 196 is held in a fixed position. A flange 199 isprovided at the base of the limiting stop, the upper surface of theflange defining a shoulder. A recess 200 is provided at the periphery ofthe flange 199' so that an instrument may be inserted into said recessfor the purpose of maintaining the limiting stop in a fixed positionwhile the piston 176 and valve stem 172 are being rotated. A set screw202 is also provided in the flange 199 to lock the limiting stop to thevalve stem once their relative position has been determined. Access tothe recess 200 and set screw 202 is provided by means of an opening 204in the hollow spacer 184. Access to the screwdriver slot 198 is providedby means of a removable plug 206 in the air cylinder cap 182. Inaddition to the shortening of the stroke of the valve stem 172, rapidseating of the valve member 168 is further aided by means of a coilspring 288 which circumscribes the upper portion of the limiting stop196 while being compressed between the lower surface of the air cylinderbase 180 and the shoulder at the base of the limiting stop. The spring208 imparts a downward motion to the valve stem 172 and thus aids thedownward motion imparted to the valve stem by the introduction ofcompressed air into air cylinder chamber 188.

To prevent improper seating of valve member 168 at valve seat 170 due topossible misalignment of the valve stem 172, the valve member isattached to the valve stem so as to allow a limited amount of universalmovement (FIGS. 11, 12). A bore 210 is centrally located in the upperportion and along the longitudinal axis of the valve member 168 so as toaccommodate the lower end of the valve stem 172, the diameter of saidbore being greater than the diameter of said valve stem. It is desirablethat the bottom of the bore 210 be flat. Another bore 212 is locatedalong the diameter of the valve stem so as to accommodate the pin 174,the ends of which are rigidly fastened to the valve member 168. The bore212 in the valve stem is of a greater diameter than that of the pin 174and is of such size as to allow the lower tip of the valve stem to be incontact with the bottom of the bore 210 in the valve member without thepin 174 making contact with the valve stem. Thus when the valve stem hasdownward motion said motion will be transmitted to the valve membersolely by means of the contact between the lower tip of the valve stemand the flat bottom of the bore 210. There being no rigid connectionbetween the valve stem and the valve member, the valve stem may slide orpivot freely at its point of contact with the bottom of the bore 210 inthe valve member 168. The lower tip of the valve stem is rounded tofacilitate such sliding or pivoting. Thus, the misalignment of the valvestem has no effect on the alignment of the valve member. The alignmentof valve member 168 with the valve seat 170 is accomplished solely bymeans of its contact with the wall of the passage in the nozzle 164. Toallow the adhesive to flow between the periphery of the valve member andthe wall of the passage in the nozzle, vertical grooves 214 are formedin the valve member at its periphery.

A removable plug 216 having a discharge orifice 218 is located at thetip of the nozzle and may be interchanged with similar plugs havingdischarge orifices of a different diameter, thereby allowing variance inthe size of the bead 220 dispensed.

The flow rate of adhesive thus may be varied by means of the pressureregulating device 73 and/or substitution of plugs 216 with differentsized discharge orifices. Once the flow rate has been determined and sofixed it is mainained at that level by means of the continuouslyoperating gear pump which subjects the adhesive to a constant pressure.When there is no flow through the nozzle and the apparatus is notdispensing, the pump continues to operate, recirculating the adhesivewithin the apparatus by means of the pressure regulating device 73.

The viscosity of the adhesive is of major importance in determining theflow rate. Should the temperature of the adhesive be allowed to vary, toany great extent the viscosity will similarly vary with the result thatthe flow rate will be uncertain. To insure arelatively constantviscosity and flow rate, the temperature of. the adhesive is maintainedat a constant level by means of electric heat-.

ing elements strategically located throughout the apparatus. The heatingelements are actuated by heat sensing elements similarly located. Inaddition to the annular heater 40 and the heating coil 136, a pair ofheating elements 222 (FIG. 6) are located in the casting of the floatchamber 33. A heat sensing element 224 (FIG. 5) is also located in saidcasting and controls the operation of heating elements 222 and annularheater 40. Electric heating elements 226 (FIG. 7) are fastened to theouter surface of the casting of the sump 48 and are actuated by a heatsensing element 228 (FIG. 1) located within said casting. A pair ofheaters 238 are located in the anchor block of the dispensing gun (FIG.10). These heaters are not controlled by any heat sensing elements andare in continuous operation.

As a safety precaution, a temperature sensing element 232 (FIG. 7) islocated within the sump 48 so as to be in direct contact with theadhesive, and is electrically integrated (FIG. 13) into the motorcircuit so that the motor 68 will not operate until the temperature ofthe adhesive has reached a level wherein it is molten. When element 232is heated to a predetermined level, a switch 233 is closed which in turnenergizes a relay 236 to close another switch 23-8. The switch isconnected in series with the motor 68 thereby precluding operation ofthe motor 68 when the switch 238 is open. A drain pipe 234 (FIG. 7) mayalso be provided for cleaning the sump.

In view of the relatively high temperatures at which the apparatus isoperated it is advisable to provide insulation 240 at points ofpatricularly high temperature, such as surrounding the sump.

When there is no workpiece 166 presented to the apparatus this conditionwill be sensed by a suitable device (micros-witch, photoelectric cell,etc.) and compressed air will be directed (through valve meansresponsive to said microswitch or photoelectric cell) to air cylinderchamber 188, thereby forcing the valve member 168 downwardly against thevalve seat 170 so as to be in a non-dispensing position as shown in FIG.12. While the apparatus is in a non-dispensing position the pump 52continues to operate so that the full flow from the pump outlet conduit72 is recirculated to the sump 48 by means of the subsidiary conduits78, 80 in the pressure regulating block 74. The adhesive in the hose 134and dispensing gun 82, being in communication with the adhesive in theprimary conduit 76, is thus subjected to the same pressure as theadhesive in said primary conduit and will immediately begin to flow ontothe workpiece 166 when the valve member 168 has retracted from the valveseat 170 and is thus in a dispensing position.

When a workpiece is presented to the apparatus, its presence issimilarly sensed with the result that compressed air is introduced intothe air cylinder chamber 190, thereby causing the valve member 168 tounseat, so that the apparatus will be in a dispensing position. When theapparatus is dispensing, the flow of adhesive from the pump outletconduit 72 is divided between the primary conduit 76 which leads to thedispensing gun 82 and the subsidiary conduits 78, 80 which lead back tothe sump 48. The proportion in which the flow of adhesive will so divideis dependent on the amount of obstruction presented to the firstsubsidiary conduit 76 by the needle valve 84 and the size of thedischarge orifice 218 in the removable plug 216.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. A dispensing gun for use in a fluid dispensing system in which thereis a source of fluid under pressure comprising:

an anchor block having a hollow interior, said hollow being incommunication with said source of fluid pressure;

a nozzle having an inlet end, an outlet end and a passageinterconnecting said inlet and outlet ends, said r nozzle being affixedat its inlet end to one end of said anchor block, said inlet end beingin communication with the hollow of said anchor block thereby allowingfluid to flow from its source into said anchor block and through saidnozzle passage;

a valve stem, coaxially located within said nozzle pas- V sage andprotruding through the other end of said anchor block; an air cylinderrigidly mounted in relation to said anchor block, said air cylinderhaving a base in which 1 an aperture is centrally located for slidableaccommodation of that end of said valve stem protruding through saidanchor block whereby said valve stem may enter said air cylinder; I apiston, slidably contained within said air cylinder thereby dividing theinterior of said air cylinder into a pair of expansible air chambers,said piston being rigidly attached to said valve stem whereby the motionof said piston will be transmitted to said valve stem;

means for introducing V compressed air into said air chamber therebyactivating said piston;

valve means located within said nozzle passage and in operativeengagement with said valve stem whereby the motion of said valve stemmay be transmitted to said valve means thereby causing said valve meansto be in an open or closed position;

a hollow spacer interposed between said air cylinder base and saidanchor block, and enclosing a portion of said valve stem;

a cup-shaped limiting stop located within said spacer and having acylindrical sidewall, a base having a tapped hole centrally locatedtherein and a peripheral shoulder located at the lower portion of saidlimiting stop, said shoulder being of a greater diameter than that ofsaid sidewall, said base being in threaded engagement with that portionof said valve stem enclosed by said spacer, the uppermost end of saidlimiting stop defining a plane normal to the longitudinal axis of saidvalve system and parallel to the plane of the lower surface of the aircylinder base, whereby upward movement of said valve stem will terminatewhen the uppermost end of said limiting stop abuts the lower surface ofsaid air cylinder, the amount of said upward movement being determinedby the clearance between the uppermost end of said limiting stop and thelower surface of said air cylinder base, said clearance being adjustableby rotation of said limiting stop about said valve stem;

means for locking said limiting stop and said valve stem in a fixedposition relative to each other;

and a helical compression spring encircling said limiting stop, thelower end of said spring abutting the shoulder of said limiting stop andthe upper end of said spring abutting the lower surface of said aircylinder base, whereby a downward force will act upon said limiting stopand valve stem, thereby increasing the speed with which said valvemember will change from an open to a closed position.

2. An apparatus as recited in claim 1 wherein said valve meanscomprises:

a valve seat located within said nozzle passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of said valve seat,said valve member having a first blind bore centrally located at itsupper end;

communicative means between the portion of said nozzle passage abovesaid valve member and the portion of said nozzle passage below saidvalve member whereby fluid contained in said upper portion underpressure may flow from said upper portion to said lower portion and thusbe dispensed upon the opening of the valve;

a pin rigidly secured to the upper end of said valve member, said pindiametrally traversing said first bore;

said valve stem having a second bore located at its lower end, saidlower end being accommodated by the first bore in the upper end of saidvalve member and secured thereto by means of mating cooperation of saidpin and the second bore in said valve stem,

said first bore being of a greater diameter than that of said valve stemand said second bore being of a greater diameter than that of said pinso that a limited amount of universal movement may exist between saidvalve stern and said valve member,

the diameter of said second bore being of such a size that the lower tipof said valve stem may be in contact with the bottom of said first borein the upper end of said valve member without said pin being in contactwith said valve stem, the point of contact being the sole point ofcontact between said valve stem and said valve member, thereby allowingsaid valve stem to pivot and slide about said point of contact,

whereby misalignment of said valve stem will have no elfect upon thealignment of said valve member with said valve seat, said valve memberbeing guided into alignment solely by means of the wall of said nozzlepassage.

3. A valve apparatus comprising:

a nozzle having a passage therein;

a valve seat formed within said passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of said valve seat, afirst blind bore centrally located at its upper end, and at least onegroove formed at its periphery so that said groove in conjunction withthe wall of said nozzle passage defines a passage leading from the upperend of said valve member to the lower end thereof, thereby allowingfluid to flow from the upper end of the nozzle passage, through thepassage defined by said groove and said wall and into a position whereit will be dispensed upon opening of the valve;

a pin rigidly mounted to the upper end of the valve member, said pindiametrally traversing the first bore;

a valve stem located within the nozzle passage and having a second borediametrally located at its lower end, said lower end being accommodatedby the first bore in the upper end of the valve member and securedthereto by means of mating cooperation of the pin and said second borein the valve stem;

the first bore being of a greater diameter than that of the valve stemand the second bore being of a greater diameter than that of the pin sothat a limited amount of universal movement may exist between the valvestem and the valve member;

the diameter of the second bore being of such a size that the lower tipof the valve stem may be in contact with the bottom of the first bore inthe upper end of the valve member without the pin being in contact withthe valve stem, said point of contact being the sole point of contactbetween the valve stem and the valve member thereby allowing the valvestem to pivot and slide about said point of contact;

whereby misalignment of the valve stem will have no effect upon thealignment of the valve member with the valve seat, said valve memberbeing guided into alignment solely by means of the wall of the nozzlepassage.

4. An apparatus as recited in claim 3 wherein:

the bottom of the first bore located in the upper end of the valvemember is flat and the lower tip of the valve stem which is in contactwith the bottom of said first bore is convex thereby minimizing the areaof contact between the valve stem and the valve member and facilitatingpivoting and sliding of the valve stem with respect to the valve member.

5. A valve apparatus comprising:

a nozzle having a passage therein;

a valve seat formed within said passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of'said valve seat anda first blind bore centrally located at its upper end;

a pin rigidly mounted to the upper end of the valve member, said pindiametrally traversing the first bore;

a valve stem located within the nozzle passage and having a second borediametrally located at its lower end, said lower end being accommodatedby the first bore in the upper end of the valve member and securedthereto by means of mating cooperation of the pin and said second borein the valve stem;

the diameter of the first bore being greater than that of the valve stemand the diameter of the second bore being greater than that of the pinso that a limited amount of universal movement may exist between thevalve stem and the valve member;

the diameter of the second bore being of such a size that the lower tipof the valve stem may be in contact with the bottom of the first blindbore in the upper end of the valve member without the pin being incontact with the valve stem, said point of contact being the sole pointof contact between the valve stem and the valve member, thereby allowingthe valve stem to pivot and slide about said point of contact;

whereby misalignment of the valve stem will have no effect upon thealignment of the valve member with the valve seat, said valve memberbeing guided into alignment by means of the wall of the nozzle passage;

means for the introduction of fluid into the nozzle passage so that itmay flow therethrough and thus be dispensed when the valve is in an openposition.

6. An apparatus as recited in claim 5 wherein:

the bottom of the first bore located in the upper end of the valvemember is flat and the lower tip of the valve stem which is in contactwith the bottom of said first bore is convex, thereby minimizing thearea of contact between the valve stem and the valve member andfacilitating pivoting and sliding of the valve stem with respect to thevalve member.

7. A valve apparatus comprising:

a nozzle having a passage therein; 7

a valve seat formed within the lower end of said passage;

a valve member slidably mounted within and guided by the wall of saidnozzle passage and having its lower end conforming to the shape of saidvalve seat and a first blind bore centrally located at its upper end;

communcative means between the portion of the nozzle passage above thevalve member and the portion of the nozzle passage below the valvemember whereby fluid contained in said upper portion under pressure mayflow from said upper portion to said lower portion and thus be dispensedupon the opening of the valve;

a pin rigidly mounted to the upper end of the valve member, said pindiametrally traversing the first bore;

a valve stem located within the nozzle passage and having a second borediametrally located at its lower end, said lower end being in a matingrelationship with the first bore in the upper end of the valve memberand secured thereto by means of mating cooperation of the pin and saidsecond bore in the valve stem;

the diameter of the first bore being greater than that of the valve stemand the diameter of the second bore eing greater than that of the pin sothat a limited amount of universal movement will be permitted betweenthe valve stem and the valve member;

the diameter of the second bore being of such a size that the lower tip'of the valve stem may be in contact with the bottom of the first blindin the upper end of the valve member without the pin being in contactwith the valve stem, said point of contact being the sole point ofcontact between the valve stem and the valve member, thereby allowingthe valve stem to pivot and slide about said point of contact;

whereby misalignment of the valve stem will have no effect upon thealignment of the valve member with the valve seat, said valve memberbeing guided into alignment by means of the wall of the nozzle passage.

8. An apparatus as recited in claim 7 wherein:

the bottom of the first bore located in the upper end of the valvemember is flat and the lower tip of the valve stem which is in contact13 with the bottom of said first bore is convex, thereby minimizing thearea of contact between the valve stem and the valve member andfacilitating pivoting and sliding of the valve stem with respect to thevalve member.

9. A dispensing gun for use in a fluid-dispensing system in which thereis a source of fluid under pressure comprising: i

an anchor block having a hollow interior, said hollow being incommunication with said source ot'fluid under pressure;

a nozzle having an inlet end, an outlet end and a passageinterconnecting said inlet and outlet end, said nozzle being aflixed atits inlet end to 'one end of said anchor block, said inlet end being incommunication with the hollow of said anchor block thereby allowingfluid to flow from its source into said anchor block and through saidnozzle passage;

a valve stem coaxially located within said nozzle passage and protrudingthrough the other end of said anchor block; means for imparting to saidvalve stem motion toward and away from said outlet end, said means beingin engagement with that portion of said valve stem protruding throughsaid anchor block;

a valve seat located within said nozzle passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of said valve seat,said valve member having a first blind bore centrally located at itsupper end;

communicative means between the portion of said nozzle passage abovesaid valve member and the portion of said nozzle pas-sage below saidvalve mem- 1 her whereby fluid contained in said upper portion underpressure may flow from said upper portion to said lower portion and thusbe dispensed upon the opening of the valve;

14 amount of said upward movement being determined by the clearancebetween the uppermost end of said limiting stop and the lowermost end ofsaid abutting means, said clearance being adjustable by rotation of saidlimiting stop about said valve stem; and means for locking said limitingstop and said valve stem in a fixed position relative to each other. 11.A dispensing gun for use in a fluid dispensing system in which there isa source of fluid under pressure comprising:

a pin rigidly secured to the upper end of said valve member, said pindiametrally traversing said first bore,

said valve stem having a second bore located at its lower end;

said lower end being accommodated by the first bore and the upper end ofsaid valve member and secured thereto by means of mating cooperation ofsaid pin and the second bore in said valve stem,

I said first bore being of a greater diameter than that of said valvestem and said second bore being of a greater diameter than that of saidpin so that a limited amount of universal movement my exist between saidvalve stem and said valve member;

the diameter of said second bore being of such a size that the lower tipof said valve stem may be in contact with the bottom of said first borein the upper end of said valve member without said pin being in contactwith said valve stem, the point of contact being the sole point ofcontact between said valve stem and said valve member, thereby allowingsaid .valve stem to pivot and slide about said point of contact, wherebymisalignment of said valve stem will have no eifect upon the alignmentof said valve member with said valve seat, said valve member beingguided into alignment solely by means of said nozzle passage.

10. An apparatus as recited in claim 9 further comprising:

a limiting stop threadably engaged with the portion of said valve stemprotruding through and beyond said anchor block;

abutting means rigidly mounted with respect to said anchor block andlocated above said limiting stop, said abutting means being soconstructed and arranged that upward movement of said valve stem willterminate when the uppermost end of said limiting stop abuts thelowermost end of said abutting means, the

an anchor block having a hollow interior, said hollow being incommunication with said source of fluid under pressure;

a nozzle having an inlet end, an outlet end and a passageinterconnecting said inlet and said outlet ends, said nozzle beingaffixed at its inlet end to one end of said anchor block, said inlet endbeing in communication with the hollow of said anchor block therebyallowing fluid to flow from its source into said anchor block andthrough said nozzle passage;

a valve stem coaxially located within said nozzle passage and protrudingthrough the other end of-- said anchor block;

means for imparting to said valve stem motion toward and away from saidoutlet end, said means being in engagement with that portion of saidvalve stem protruding through said anchor block;

means for varying the distance that said valve stem may be withdrawnfrom said outlet end;

a valve seat located within said nozzle passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of said valve seat,said valve member having a first blind bore centrally located at itsupper end;

communicative means between the portion of said nozzle passage abovesaid valve member and the portion of said nozzle passage below saidvalve member whereby fluid contained in said upper portion underpressure may flow from said upper portion to said lower portion thus bedispensed uponthe opening of the valve;

a pin rigidly secured to the upper end of said valve member, said pindiametrally traversing said first 'bore,

said valve stem having a second bore located at its lower end, saidlower end being accommodated by the first bore in the upper end of saidvalve member and secured thereto by means of mating cooperation of saidpin and the second bore in said valve stem,

said first bore being of a greater diameter than that of said valve stemand said second bore being of a greater diameter than that of said pinso that a limited amount of universal movement may exist between saidvalve stem and said valve member,

the diameter of said second bore being of such a size that the lower tipof said valve stem may be in contact with the bottom of said first borein the upper end of said valve member without said pin being in contactwith said valve stem, the point of contact being the sole point ofcontact between said valve stem and said valve member, thereby allowingsaid valve stem to pivot and slide about said point of contact, wherebymisalignment of said valve stem will have no elfect upon the alignmentof said valve member with said valve seat, said valve member beingguided into alignment solely by means of the wall of said nozzlepassage.

12. An apparatus as recited in claim 11, wherein the means for varyingthe distance that said valve stem may be withdrawn from said outlet endcomprises? a limiting stop threadably engaged with the portion of saidvalvestem protruding through and beyond said anchor block; abuttingmeans rigidly mounted with respect to said anchor block and locatedabove said limiting stop, said abutting means being so constructed andarranged that upward movement of said valve stem will terminate when theuppermost end of said limiting stop abuts the lowermost end of saidabutting means, the amount of said upward movement being determined bythe clearance between the uppermost end of said lirnting stop and thelowermost end of said abutting means, said clearance being adjustable byrotation of said limiting stop about said valve stem; and

means for locking said limiting stop and said valve stem in a fixedposition relative to each other.

13. A dispensing gun for use in a fluid dispensing system in which thereis a source of fluid under pressure comprising:

an anchor block having a hollow interior, said hollow being incommunication with said source of fluid under pressure; p

a nozzle having an inlet end, an outlet end and a passageinterconnecting said inlet and outlet ends, said nozzle being affixed atits inlet end to one end of said anchor block, said inlet end being incommunicaiton with the hollow of said anchor block thereby allowingfluid to flow from its source into said anchor block and through saidnozzle passage;

a valve stem coaxially located within said nozzle passage and protrudingthrough the other end of said anchor block;

an air cylinder rigidly mounted in relation to said anchor block saidair cylinder having a base in which an aperture is centrally located forslidable acccommodation of that end of said valve stem protrudingthrough said anchor block whereby said valve stem may enter said aircylinder;

a piston, slidably contained within said air cylinder thereby dividingthe interior of said air cylinder into a pair of eXpansible airchambers, said piston being rigidly attached to said valve stem wherebythe motion of said piston will be transferred to said valve stem;

means for introducing compressed air into said air chambers therebyactivating said piston;

a valve seat located within said nozzle passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of valve seat, saidvalve member having a first blind bore centrally located at its upperend;

communicative means between the portion of said nozzle passageabove saidvalve member and the portion of said nozzle passage below said valvemember whereby fluid contained in said upper portion under pressure mayflow from said upper portion to said lower portion and thus be dispensedupon the opening of the valve;

a pin rigidly secured to the upper end of said valve member, said pindiametrally traversing said first bore,

said valve stem having a second bore located at its lower end, saidlower end being accommodated by the first bore in the upper end of saidvalve member and secured thereto by means of mating cooperation of saidpin in the second bore in said valve stem,

said first bore being of a greater diameterthan that of said valve stemand said second bore being of a greater diameter than that of said pinso that a limited amount of universal movement may exist between saidvalve stem and said valve member, the diameter of said second bore beingof such a size that the lower tip of said valve stem may be in contactwith the bottom of said first bore in the upper end of said valve memberwithout said pin being in contact with said valve stem, the point ofcontact being the sole point of contact between said valve stem and temin which there is a source of fluid under pressure comprising:

an anchor block having a hollow interior, said hollow being incommunication with said source of fluid under pressure;

a nozzle having an inlet end, an outlet end, and a passageinterconnecting said inlet and outlet ends, said nozzle being aflixed atits inlet end to one end of said anchor block, said inlet end being incommunication with the hollow of said anchor block thereby allowingfluid to flow from its source into said anchor block and through saidnozzle passage;

21 valve stem, coaxially located within said nozzle passage andprotruding through the other end of said anchor blocl an air cylinderrigidly mounted in relation to said anchor block said air cylinderhaving a base in which an aperture is centrally located for slidableaccommodation of that end of said valve stem protruding through saidanchor block whereby said valve stem may enter said air cylinder;

a piston slidably contained within said air cylinder thereby dividingthe interior of said air cylinder into a pair of expansible airchambers, said piston being rigidly attached to said valve stem wherebythe motion of said piston will be transmitted to said valve stem;

means for introducing compressed air into said air chambers therebyactivating said piston;

means for varying the distance that said valve stem may be withdrawnfrom said outlet end;

a valve seat located within said nozzle passage;

a valve member slidably mounted within and guided I by said nozzlepassage and having its lower end conforming to the shape of said valveseat, said valve member having a first blind bore centrally located atits upper end;

communicative means between the portion of said nozzle passage abovesaid valve member and the portion of said nozzle passage below saidvalve member whereby fluid contained in said upper portion underpressure may flow from said upper portion to said lower portion and thusbe dispensed upon the opening of the valve;

a pin rigidly secured to the upper end of said valve member said pindiametrally traversing said first bore,

said valve stem having a second bore located at its lower end, saidlower end being accommodated by the first bore in the upper end of saidvalve member and secured thereto by means of mating cooperation of saidpin and the second bore in said valve stem, said first bore being of agreater diameter than that of said valve stem and said second bore beingof a greater diameter than that of said pin so that a limited amount ofuniversal movement may exist between said valve stem and saidvalvemember;

the diameter of said second bore being of such a size that the lower tipof said valve stem may be in contact with the bottom of said first borein the upper end of said valve member without said pin being in contactwith said valve stem, the point of contact between said valve stem andsaid valve member, thereby allowing said valve stem to pivot and slideabove said point of contact whereby misalignment of said valve stem willhave no effect upon the alignment of said valve member with said valveseat, said 17 valve member being guided into alignment solely by meansof the wall of said nozzle passage. 15. A dispensing gun for use in afluid dispensing system in which there is a source of fluid underpressure comprising:

an anchor block having a hollow interior, said hollow being incommunication with said source of fluid under pressure;

a nozzle having an inlet end, an outlet end, and a passageinterconnecting said inlet and outlet ends said nozzle being aflixed atinlet end to one end of said anchor block, said inlet end being incommunication with the hollow of said anchor block thereby allowingfluid to flow from its source into said anchor block through said nozzlepassage;

a valve coaxially located within said nozzle passage and protrudingthrough the other end of said anchor block;

an air cylinder rigidly mounted with relation to said anchor block, saidair cylinder having a base in which an aperture is centrally located forslidable end of that end of said valve stem protruding through saidanchor block whereby said valve stem may enter said air cylinder;

a piston slidably contained within said air cylinder thereby dividingthe interior of said air cylinder into a pair of expansible airchambers, said piston being rigidly attached to said valve stem wherebythe motion of said piston may be transmitted to said valve stem;

means for introducing compressed air into said air chambers therebyactivating said piston;

a hollow spacer interposed between said air cylinder base and saidanchor block and enclosing a portion of said valve stem;

a limiting stop, located within said hollow spacer and threadablyengaged to that portion of said valve stem enclosed by said hollowspacer, the uppermost end of said limiting stop being located directlybelow the bottom surface of said air cylinder base, whereby upwardmovement of said valve stem will terminate when the uppermost end ofsaid limiting stop abuts the bottom surface of said air cylinder base,the amount of said upward movement being determined by the clearancebetween the uppermost end of said limiting stop and the bottom surfaceof said air cylinder base, said clearance being adjustable by rotationof said limiting stop above said valve stem;

means for locking said limiting stop in said valve stem in a fixedposition relative to each other; and

valve means located within said nozzle passage and in operativeengagement with said valve stem whereby motion of said valve stem may betransmitted to said valve means thereby blocking or unblocking saidnozzle passage.

16. An apparatus as recited in claim 15- wherein said valve meanscomprises:

a valve seat located within said nozzle passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of said valve seat,said valve member having a first blind bore centrally located at itsupper end;

communicative means between the portion of said nozzle passage abovesaid valve member and the portion of said nozzle passage below saidvalve member whereby fluid contained in said upper portion underpressure may flow from said upper portion to said lower portion and thusbe dispensed upon the opening of the valve;

a pin rigidly secured to the upper end of said valve member, said pindiametrally traversing said first bore,

said valve stem having a second bore located at its lower end, saidlower end being accommodated by the first bore in the upper end of saidvalve member and secured thereto by means of mating cooperation of saidpin and the second bore in said valve stem,

said first bore being of a greater diameter than that of said valve stemand said second bore being of a greater diameter than that of said pinso that a limited amount of universal movement may exist between saidvalve stem and said valve member,

the diameter of said second bore being of such a size that the lower tipof said valve stem may be in contact with bottom of said first bore inthe upper end of said valve member without said end being in contactwith said valve stem, the point of contact being the sole point ofcontact between said valve stem and said valve member thereby allowingsaid valve stem to pivot and slide above said point of contact wherebymisalignment of said valve stem will have no effect upon the alignmentof said valve member with said valve seat, said valve members beingguided int-o alignment solely by means of the wall of said nozzlepassage.

17. A dispensing gun for use in a fluid dispensing system in which thereis a source of fluid under pressure comprising:

an anchor block having a hollow interior, said hollow being incommunication with said source of fluid under pressure;

a nozzle having an inlet end, an outlet end and a passageinterconnecting said inlet and outlet ends, said nozzle being afiixed atits inlet end to one end of said anchor block, said inlet end being incommunication with the hollow of said anchor blockthereby allowing fluidto flow from its source into said anchor block through said nozzlepassage;

a valve stem coaxially located within said nozzle passage and protrudingthrough the other end of said anchor block;

an air cylinder, rigidly mounted in relation to said anchor block, saidair cylinder having a base in which an aperture is centrally located forslidable accommodation of that end of said valve stem protruding throughsaid anchor block whereby said valve stem may enter said air cylinder;

a piston slidably contained within said air cylinder thereby dividingthe interior of said air cylinder into a pair of expansible airchambers, said piston being rigidly attached to said valve stem wherebythe motion of said piston will be transmitted to said valve stem;

means for introducing compressed air into said air chambers therebyactivating said piston;

a valve seat located within said nozzle passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of said valve seat,said valve member having a first blind bore centrally located at itsupper end;

communicative means between the portion of said nozzle passage of abovesaid valve member and the portion of nozzle passage below said valvemember whereby fluid contained in said upper portion under pressure mayflow from said upper portion to said lower portion and thus be dispensedupon the opening of the valve;

a pin rigidly secured to the upper end of said valve member, said pindiametrally traversing said first bore;

said valve stem having a second bore located at its lower end, saidlower end being accommodated by the first bore in the upper end of saidvalve member and secured thereto by means of mating cooperation of saidpin and the second bore in the said valve stem;

said first bore being of a greater diameter than that of said valve stemand said second bore being of 19 a greater diameter than that of saidpin so that a limited amount of universal movement may exist betweensaid valve stem and said valve member;

the diameter of said second bore being of such a size that the lower tipof said valve stem may be in contact with the bottom of said first borein the upper end of said valve member without said pin being in contactwith said valve stem, the point of contact being the sole point ofcontact between said valve stem and said valve member, thereby allowingsaid valve stem to pivot and slide above said point of contact wherebymisalignment of said valve stem will have no effect upon the alignmentof said valve member with said valve seat, said valve member beingguided into alignment solely by means of the wall of said nozzlepassage: and bias means so constructed and arranged as to urge saidvalve member into a blocking relation with said nozzle passage wherebysaid bias means may aid the action of said air cylinder and piston incausing said valve to convert from an unblocking to a blocking relationwith said nozzle passage.

18. An apparatus as recited in claim 17 further comprising:

means for varying the distance which said valve stem may be withdrawnfrom said outlet end. 19'. An apparatus as recited in claim 18 whereinthe means for varying the distance which said valve stem may bewithdrawn from said outlet end comprises:

a hollow spacer interposed between said air cylinder base and saidanchor block and enclosing a portion of said valve stem;

a limiting stop located within said hollow spacer and threadably engagedso that portion of said valve stem enclosed by said hollow spacer, theuppermost end of said limiting stop being located directly below thebottom surface of said air cylinder base, whereby upward movement ofsaid valve stem will terminate when the uppermost end of said limitingstop abuts the bottom surface of said air cylinder base, the amount ofsaid upward movement being determined by the clearance between theuppermost end of said limiting stop and the bottom surface of said aircylinder base, said clearance being adjustable by rotation of saidlimiting stop about said valve stem; and

means for locking said limiting stop and said valve stem in a fixedposition relative to each other.

20. An apparatus as recited in claim 19 wherein the valve meanscomprises:

a valve seat located with said nozzle passage;

a valve member slidably mounted within and guided by said nozzle passageand having its lower end conforming to the shape of said valve seat,said valve member having a first blind bore centrally located at itsupper end;

communicative means between the portion of said nozzle passage abovesaid valve member and the portion of said nozzle passage below saidvalve member whereby fluid contained in said upper portion underpressure may flow from said upper portion to said lower portion and thusbe dispensed upon the opening of the valve;

a pin rigidly secured to the upper end of the said valve member, saidpin diametrally traversing said first bore,

said valve stem having a second bore located at its lower end, saidlower end being accommodated by the first bore in the upper end of saidvalve member and secured thereto by means of mating cooperation of saidpin and the second bore in said valve stem,

said first bore being of a greater diameter than that of said valve stemand said second bore being of a greater diameter than that of said pinso that a limited amount of universal movement may exist between saidvalve stem and said valve member,

the diameter of said second bore being of such a size that the lower tipof said valve stem may be in contact with the bottom of said first boreand the upper end of said valve member without said pin being in contactwith said valve stem, the point of contact being the sole point ofcontact between said valve stem and said valve member, thereby allowingsaid valve stem to pivot and slide about said point of contact, wherebymisalignment of said valve stem will have no effect upon the alignmentof said valve member with said valve seat, said valve member beingguided into alignment solely by means of a wall of said nozzle passage.

21. A valve apparatus comprising:

a nozzle having a passage therein and an outlet orifice in communicationwith said passage;

a valve member contained within said nozzle passage for movement thereinbetween a first position wherein said valve member is remote from saidoutlet orifice and a second position wherein said valve member is inobstructing relation with said out-let orifice;

means for guiding said valve member along said passage in a path that isin paralleling relationship to axis of said nozzle passage, said guidemeans being effective to so guide said valve member during the entirerange of movement of said valve member between said first and secondpositions;

a valve stem located within said nozzle passage;

means providing a non-rigid connection between said valve member andsaidvalve stem to effect said movement of said valve member and to as topermit 7 References Cited UNITED STATES PATENTS 445,127 1/1891 Rand251-87 X 853,769 5/1907 Caviglia. 1,261,495 4/1918 Doolin. 1,799,6674/1931 Ziegler 251-87 1,942,609 1/ 1934 Ludwig 222-309 X 2,019,50211/1935 Osgood 222-504 2,307,291 1/1943 Packwood 222-181 X 2,557,3746/1951 Cripe 222-181 X 2,599,686 6/1952 Bowman 222-181 X 2,640,6306/1953 Genco 222-510 X 2,645,383 7/1953 Miller 222-1-85 X 2,886,2105/1959 Cooper et a1 222-1 2,900,109 8/1959 Hoopes et al. 222-1 3,005,47410/1961 Merchant 222-50'4 X 3,081,913 3/1963 Rotter 222-250 3,094,2546/1963 Cullen et al. 222-504 3,095,125 6/1963 Bundy 222-30'9 3,116,07912/1963 Doolittle 287-20 3,130,876 4/1964 Baker 222-146 3,160,33112/1964 Trumbull et al. 222-309 3,162,217 12/ 1964 Poli et al. 222-309 X3,164,172 1/1965 Lee 137-6121 3,204,828 9/1965 Paulsen 222-146 3,207,1799/1965 Klagues 137-6121 3,236,548 2/1966 Osgood 287-20 FOREIGN PATENTS1,289,845 2/ 1962 France.

RAPHAEL M. LUPO, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,332,581 July 25, 1967 Roger S. Estabrooks It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 12 line 61 for "blind" read bore column 17, line 16, for "valve"read valve stem Signed and sealed this 9th day of July 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

21. A VALVE APPARATUS COMPRISING: A NOZZLE HAVING A PASSAGE THEREIN ANDAN OUTLET ORIFICE IN COMMUNICATION WITH SAID PASSAGE; A VALVE MEMBERCONTAINED WITHIN SAID NOZZLE PASSAGE FOR MOVEMENT THEREIN BETWEEN AFIRST POSITION WHEREIN SAID VALVE MEMBER IS REMOTE FROM SAID OUTLETORIFICE AND A SECOND POSITION WHEREIN SAID VALVE MEMBER IS INOBSTRUCTING RELATION WITH SAID OUTLET ORIFICE; MEANS FOR GUIDING SAIDVALVE MEMBER ALONG SAID PASSAGE IN A PATH THAT IS IN PARALLELINGRELATIONSHIP TO AXIS OF SAID NOZZLE PASSAGE, SAID GUIDE MEANS BEINGEFFECTIVE TO SO GUIDE SAID VALVE MEMBER DURING THE ENTIRE RANGE OFMOVEMENT OF SAID VALVE MEMBER BETWEEN SAID FIRST AND SECOND POSITIONS; AVALVE STEM LOCATED WITHIN SAID NOZZLE PASSAGE; MEANS PROVIDING ANON-RIGID CONNECTION BETWEEN SAID VALVE MEMBER AND SAID VALVE STEM TOEFFECT SAID MOVEMENT OF SAID VALVE MEMBER AND TO AS TO PERMIT A LIMITEDAMOUNT OF MOTION BETWEEN SAID VALVE MEMBER AND VALVE STEM;